Some of the most important seabird colonies in Western Europe are under threat because their main source of food seems to be disappearing.

The Royal Society for the Protection of Birds Scotland (RSPB) is blaming the shortage on climate change.

RSPB Scotland said the population in Shetland was facing a crisis and this summer is expected to witness a record low number of seabirds.

Most of the seabirds feed on sand eels which are in short supply.

The sheer cliffs of Shetland should be the place to see puffins, gannets and skuas, but ornithologists say the great seabird colonies are shrinking.

Many birds are too hungry to lay eggs.

This has been an almost unbelievably bad breeding season

Martin HeubeckAberdeen University

No Arctic tern or Kittiwake chicks have been reared in southern Shetland.

There are few Guillemot chicks and the number of Great Skuas - known as bonxies - has fallen.

Most of the seabirds depend on sand eels - which used to shoal in vast numbers.

Shetland fishermen have stopped catching them, but scientists believe climate change could be to blame for their continued decline, which is causing the birds to starve.

Sea temperatures have risen by up to two degrees in the past 20 years and that may be causing the sand eels and the plankton on which they depend to move to cooler waters.

Inquiry demand

Experts say last year was bad, but this one's worse.

Martin Heubeck, of Aberdeen University, said: "This has been an almost unbelievably bad breeding season. The scale of the breeding failure of guillemots is unprecedented in Europe."

Pete Ellis, of the RSPB in Shetland, added: "The situation is still getting worse for our struggling seabirds.

"The failure of almost all great skuas to rear young is unprecedented, and the populations of some species such as Arctic skuas are now reaching critical levels and the future for them looks bleak here".

The charity demanded an urgent investigation into the problem, and tougher new conservation laws.